828 8DMMARY OF CURRENT RESEARCHES RELATING TO 



a bcll-jar. These manipiilatinus are carried out in a dark room, and 

 having been finished the apparatus is phiced in the sunlight about half a 

 minute. The paper is next repeatedly washed in a dark room to remove 

 the excess of silver, then placed in a gold chloride bath, and afterwards 

 fixed in one of hyposulphite of soda. After this it is well washed and 

 finally dried. 



Babes' modified Cultivation Vessel.* — In fig. 151 is shown Dr. V. 

 Babes' recent modification of his cultivation capsule. In this the edge 

 of the lower pan is made oblique, a, so that the agar does not slip 

 down when the capsule is turned about in microscopical examination. 



Fig. 151. 



The cnndmsation water v.ow no longer drops upon the cultivation, but 

 luns away down a fissure between the upi)er and lower pans (at c). 

 Vessels made with this shape are much less exposed to infection from 

 without than those with parallel edges. The cultivation can be closed 

 up by means of a rubber ring c. 



Cooler for quickly setting Gelatin Plates.t — Dr. A. Pfeifer recom- 

 mends instead of the glass apparatus usually employed, a box made of 

 zinc plate (the sides = 25 cm. each, and the height = I5-2 cm.) and 

 supported at each corner on cast-iron feet. When filled with water tho 

 box may be made to acquire any temperature. Water from 8^-10° R. 

 suffices to set gelatin in a very short time, and when manipulating 

 agar plates, warm water may be used to prevent the agar from setting 

 too quickly. This apparatus does away with ice, is very cheap, certain, 

 and saves a lot of time. 



Collecting and Preparing Gharaceae4 — Mr. T. F. Allen says that 

 to gather Characeai successfully a dredge must be used ; for shallow 

 water a small fine-toothed rake is preferred, but for deeper water (one 

 rarely finds them at a greater depth than 10 feet) the dredge and line 

 are essential. The best dredge for all purposes is the one recommended 

 by Prof. Nordstedt, made as follows: — A disc of lead about 3 in. diam., 

 and 3/4 in. thick has imbedded in its circumference a row of hooks, 

 about 10 in number ; through the centre of this disc is passed an iron 

 rod, which projects about 3 in. below the disc, and about 9 in. above ; to 

 the ring in the upper end toward which the points of the hooks are 

 directed, a cord is attached. The dredge weighs about 2^ lb., and catches 

 all sorts of " weeds " growing on the bottom. 



The dissection of these plants is perfectly simple. The delicate 

 species are placed in water until their normal form is restored (if they 

 have been dried), and a portion is put in a " cell " on a glass slide, and 

 examined under a 2 in. objective ; sometimes, but rarely, a higher power 



* Cuntralbl. f. Bakteriol. u. Parasitenk., iv. (1888) p. 26 (1 fig.). 



t Deutsche Med. Woclienschr., 1887, No. 42. 



t • The Oharaceae of America.' Cf. Amer. Naturalist, xsii. (1888) pp. 455-7. 



